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Delta(U) = Cvdelta(T) for Ideal Gases?

  1. Feb 28, 2015 #1
    I don't understand how Delta(U) = Cvdelta(T) is always true for Ideal Gases....Shouldn't this only be true for constant volume processes? Yet it seems to be used even when a gas is expanding or being compressed...

    Any ideas...Thanks in advance.
  2. jcsd
  3. Feb 28, 2015 #2


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  4. Feb 28, 2015 #3
    The internal energy of an ideal gas is a function only of temperature. We know this because, if you have a real gas at low pressure in half of a rigid container and vacuum in the other half, and you break the seal, after the system has re-equilibrated at a lower pressure, the temperature does not change. This shows that the internal energy does not depend on pressure. A real gas in the limit of low pressures is what we refer to as an ideal gas.

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